Worried about what medical conditions are lurking in your family tree? Breast or ovarian cancer? Huntington's disease? Gene testing, or genetic testing, may offer knowledge but not always comfort. So when is gene testing helpful and when should you steer clear? Read on for the answers...

Seven years ago, when she considered marriage and children, Anna Gorman decided to be tested for the BRCA1 and 2 gene mutations because ovarian cancer killed her grandmother and aunt.

She tested positive for BRCA1, which raises the risk of breast cancer up to 85% by age 70 and ovarian cancer by 55%.

“I wasn’t surprised, but I was upset and overwhelmed,” says Gorman, now a 35-year-old Los Angeles journalist.

So she then married her longtime boyfriend, gave birth to two daughters and had her ovaries removed by age 32.

Three years later, she had a double mastectomy.

The surgeries were hard. Still, she was relieved when it was over.

“It’s a dramatic step to take, but … lots of people get cancer and die,” she says. “I could do something about it.”

Like Gorman, many women worry about diseases that lurk in their family trees. In fact, they lead the pack when seeking genetic information.

Screening for cystic fibrosis numbered in the thousands a decade ago; today millions undergo the testing, says Steve Keiles, M.S., president of the National Society of Genetic Counselors and director of Genetic Counseling at Ambry Genetics in Aliso Viejo, Calif.

In 1999, only 415 labs tested for 704 diseases.

Today, more than 600 laboratories worldwide are equipped to test for 1,794 diseases; 1,185 clinics provide counseling, according to GeneTests at NCBI, a medical genetics information resource at the University of Washington in Seattle.

What gene testing revealsWhy do so many women go for testing? Besides diagnosing and predicting diseases, genetic tests also:

Determine if a patient carries gene mutations for disorders that might be passed to children

Assess the health of a fetus (if it is at risk for inheriting a condition)

Screen fertilized eggs before implantation

Screen newborns at risk for genetic disorders that should be treated immediately

Home-testing kitsIf you won’t see a physician because of privacy concerns or live in a remote area far from genetic-counseling centers, online companies offer home testing kits for common diseases, such as some breast and colon cancers, autoimmune disorders, macular degeneration and cardiovascular disease.

With the kits, you take a blood test or mouth swab and then send it to a laboratory. (Prices for online kits and mainstream clinical tests vary widely, depending on the services and tests ordered. At-home genetic tests can be pricey, from $295-$1,200.)

But beware: Some online companies offer a look at your genetic background for entertainment, not medical, purposes. And some don’t look for gene mutations, an often vital component when looking for diseases.

Also, home tests may not be accurate for some conditions, such as diabetes.

There’s “no reliable screening for type 2 diabetes,” Keiles says. “You can tell a lot just from your family history."

How online tests workBut there’s more to DNA testing than just getting results. Some tests are tough to interpret because of the procedure’s complexity and multilayered findings. And not all labs have trained genetics counselors to read them.

Navigenics, a San Francisco Bay Area-based online company, offers genetic counseling along with test kits and advises customers to seek tests the company doesn’t offer when appropriate, says Elissa Levin, director of genetics counseling. Counselors also follow up with phone calls after results are sent, she says.

But women with family histories of diseases such as breast and uterine cancer, Huntington’s disease and muscular dystrophy should seek genetic counseling first to make sure they’re proper candidates for testing, genetic counselors say.

For example, during counseling for Alzheimer’s – which you may not get even if you test positive – counselors sometimes find that you’re at higher risk for a more preventable health problem, such as heart disease. So they may recommend relatively inexpensive diagnostic blood tests along with lifestyle and diet changes.

Getting TestedIf you want counseling or testing, the National Society of Genetic Counselors can provide names of counselors by location, as well as guidelines for choosing a professional and getting the most out of the sessions.

Counseling alone costs about $400 and the cost of genetic tests range from $700-$4,000, Gordon says. It typically takes 2-6 weeks to get results, but some are available in days.

You also can ask your doctor for a referral; it may be covered by your health insurance plan.

The results won’t affect your rates because information the tests glean is private: In 2008, Congress passed the Genetic Nondiscrimination Information Act, which protects patients against discrimination by an insurer or employer based on genetic information. For many insurance plans, the law went into effect in May.

Who should be tested?But genetic tests aren’t for everyone. For one thing, many of the disorders they detect are rare, Keiles says.

“Most testing is targeted to ethnic groups,” for example, Tay-Sachs for people of Jewish descent and sickle-cell disease for African Americans, he says.

And gene testing for most cancers is unnecessary because about 90% of them aren’t inherited, he says.

With some diseases, such as amyotrophic lateral sclerosis — commonly known as Lou Gehrig’s disease — a positive result won’t lead to better treatment or prevention.

“I don’t want to put patients through that if all I’m doing is giving them anxiety,” GenRISK’s Gordon says.

“Sometimes, too much information can be bad,” said Peter Weiss, M.D., a Beverly Hills, Calif. obstetrician and gynecologist. “Patients need to weigh the risks and rewards of the information they get from testing and be ready to deal with [it].”

But that may change with scientific advances. The future of genetic testing centers around whole-genome sequencing, said David Stillman, a pathology professor at the University of Utah.

That process — which may be routine in 10-15 years — will allow scientists to sequence not just for one gene, such as the BRCA mutation or cystic fibrosis carriers, but all of a person’s DNA to get a better picture of the medical problem he or she may face. (The expensive process has been done on only four or five people so far.)

Common Genetic TestsHere's a guide to the most common genetic tests and those who should consider having them:

1. Down SyndromeThisgenetic disorder occurs in one out of every 700-800 infantsandcauses lifelong mental retardation, developmental delays and other problems.

Screening forDown syndrome is a routine part of prenatal care. Your obstetrician will typically do an ultrasound and blood test in the first trimester, then a “quad screen” blood test at 15-20 weeks.

If tests are positive, the next step is chorionic villus sampling (CVS), in which cells are taken from the mother’s placenta at nine to 14 weeks, or amniocentesisafter 15 weeks, in which a sample of amniotic fluid surrounding the fetus is withdrawn with a needle inserted into the woman’s uterus.

Who should have the test? Older pregnant women becausethe risk of conceiving a Down syndrome baby at age 35 is one in 400. By age 45, it’s one in 35. Also at higher risk are those with a Down syndrome child and men couples who are carriers. The screening is common among pregnant women of all ages.

Pros: Both amniocentesis and CVS are 98%-99% accurate.

Cons:There's a 1-in-200 risk of miscarriage from amniocentesis and a 1-in-100 risk from CVS.

Cost: Both procedures average about $1,500, which many insurance plans cover.

2. Neural tube defectsNeural tube defects — including spina bifada, anencephaly and encephalocele — are openings in the spinal cord or brain and are among the most common birth defects.

Who should have the test? Women who have had a fetus or baby with neural tube defects. Those with folic acid deficiencies have a higher risk for the defects. Many pregnant women have one of the tests for routine prenatal care.

Pros: Parents can prepare for the special medical care that babies with the defects will need.

Cons: Amniocentesis raises miscarriage risks.

Cost: The MSAFP blood test is about $162 in California; costs may vary in other states. The high-resolution ultrasound costs from $300-$500. Amniocentesis and CVS each costs about $1,500.

3. BRCA1 and BRCA2 genesThe letters stand for breast cancer susceptibility genes 1 and 2, respectively. They are tumor suppressors and mutations have been linked to hereditary breast and ovarian cancer.

The procedure is a simple blood test, which can be done in a doctor’s office.Who should have the tests: The gene mutations are most common in Jews of Ashkenazi, or Eastern European, descent. Those with a first-degree relative (mother, daughter or sister) or two second-degree relatives (aunt, grandmother) diagnosed with breast or ovarian cancer should consider testing.

Other women with two first-degree relatives diagnosed with breast or ovarian cancer before age 50 should also consider it.

Pros: Learning that you don’t have the mutation can relieve you of worry and avoid costly preventive procedures.

Cons: If the test is positive, you may become anxious and depressed. A counselor can help you consider preventive measures, such as having your breasts and ovaries removed.

Cost: From several hundred dollars to $3,200, depending on the extent of the testing.

4. Cystic FibrosisAn inherited chronic disease, cystic fibrosis affects the lungs and digestive systems of about 30,000 children and adults in the U.S.

A sweat test is the gold standard for diagnosis; People with CF have a higher level of chloride (salt) in their perspiration. A chemical to induce sweating is applied to an arm or leg. The liquid is then collected and analyzed in a lab.

A blood test can determine if you carry one or more CF gene mutations and how many copies of each.

With a positive test result, the next step is genetic testing to see which mutation you have. Screening newborns for CF is routine in most states.

Who should have the tests? More than 10 million Americans with no symptoms are carriers of the defective cystic fibrosis gene. The blood test helps detect carriers who may pass CF to their children.

To get the disease, a child must inherit one copy of the defective CF gene from each parent. The American College of Obstetrics and Gynecologists recommends that all couples considering having a child — and pregnant women — have the genetic-carrier testing done.

Pros: Carriers can make an informed decision about family planning, with the help of genetic counseling.

By testing their child, they can find out early if he or she has the disease and from which mutations. Early treatment and preventive measures help because symptoms often don’t show up until degeneration has begun.

Cons: Getting a positive CF diagnosis often is stressful and upsetting to parents.

Cost: Sweat tests usually cost about $300 at CF-accredited centers.

A limited mutation panel (23-97 mutations) to see if you’re a carrier typically runs about $400-$500; a comprehensive sequence analysis (more than 1,500 mutations) costs about $2,500.

Mutation testing for those already diagnosed with CF sometimes can be done with the carrier panel, but if that doesn’t find the mutations, a sequence test will cost $2,500-$3,200 for more results.

A blood test can detect the defective form of hemoglobin that causes the disease. Newborns are routinely screened for it.

In pregnant women, amniocentesis or chorionic villus (CVS) sampling will detect the disease.

Who should have the test? The gene is common among people of African, Mediterranean, Middle Eastern and East Indian ancestry. In the U.S., African Americans and Latinos are more commonly affected.

Both parents must carry a sickle cell gene for their baby to be born with the disease. Carriers — those with no symptoms — may pass it on to their children. Those with a sister or brother with the disease are at higher risk.

Cons: If the screening is positive, more tests are needed to determine the number of sickle cells present. There are risks of miscarriage associated with amniocentesis and CVS screenings.

Cost: The hemoglobin test runs about $75; DNA tests are about $300.

Will You See Your 80th Birthday?What is your life expectancy? Can you rely on good genetics to keep you thriving through the years, or do you need to do more to raise your odds of living longer? Find out your chances of making it to age 80 in this life-expectancy quiz.

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